Chevrolet designed an overdrive transmission, namely, the 700 R4, specifically for a Chevrolet engine and specifically for a specific Chevrolet bolt pattern in the transmission housing. The 700 R4 and 4L80-E transmissions were favored when introduced because of the advantage of thirty percent overdrive, and the advantage of a lower first gear ratio of 3.06 to 1.00.
Subsequent Chevrolet transmission housings, as well as other transmission housings for General Motors vehicles, including Oldsmobile, Pontiac, Cadillac, and Buick, have a transmission case with a different bolt pattern, and thus would not permit use of the advantageous 700 R4 or 4L80-E transmissions.